Theta THM989 vs DS405BLHV

A servo matchUP (comparison article) comes about from time to time and nearly always in response to a question regarding a specific servo like; I’ve been using Hitec D645MW servos for years but a buddy said I should look at ProModeler, so what have you got to compare, and what recommends them? . . . or words to that effect.

The answer to the above is a ProModeler DS180DLHV and because we don’t hide from these questions, we buy competing servos, and take them apart to show you what’s what using side-by-side photos. This, so you can suss out which side of the bread is buttered for yourself because ‘nobody’ likes being told what to do!

Note this example photo . . .

Intro

This Theta THM989 vs ProModeler DS405BLHV matchUP came about in part because of a forum post disparaging the product within a thread related to Skywing 67″ Extra NG, one of their PNP series of models and which I’ve linked here for the curious.

Note; when clicked, this link (as do others within this article), open in their own browser tab, so you don't lose your place within 'this' article!

So while it’s unusual for me to get involved in a forum discussion about servos when it’s not my product, I nevertheless opened my yap in the product’s defense. Why? Simple, in part, because I didn’t feel what was going down was quite fair.

But also in part because I’d already purchased a couple to look over (for reasons that will become clear in a moment). So because I’d seen enough of the servos to form a judgement, I disagreed with the basic premise saying the THM989 servos were the root cause leading to the crash. Saying these are basically decent servos and thus, I couldn’t keep my mouth shut (think Ford defending Chevy, amazingly enough).

As for ‘why’ we already had some Theta THM989 servos, it’s because someone had written asking my opinion about them, so answering meant actually knowing what I was talking about! And obviously, this meant having some in hand to closely examine and photograph. The only way to do that was to go out and buy some!

Anyway, here’s what he wrote, which got this started . . .

I’m looking at buying a Skywing 67" Extra NG and they offer the model in my choice of components to include MKS HV747 mini servos, or as a PNP version with Theta THM989 mini-servos pre-installed.

I've never heard of this brand and my pal Andrew said I should look at ProModeler DS405BLHV servos. Thing is, the MKS are 208oz-in and the Theta are 319oz-in but what I'm really wondering is what makes all these servos so God damned expensive?  

I'm willing to pay for top shelf products but crap, this is an awful lot of money! What else have you got to look at? Do I really need so much servo? What else have you got less expensive?

. . . thus, in explanation for what I was doing within a thread about the PNP version of the Skywing 67in Extra NG, I was doing a bit of background research regarding the model itself. This, expressly because of his asking me about servos for his new model.

So as part of learning more about it with regard to how much servo he really needed, I found myself in a forum thread and embroiled up to my neck! And all this, because our Q&A extended over the better part of a week. Quite honestly? I could sense he was a bit desperate about spending for a set of servos and perhaps most importantly, worried about pissing away his money on an unknown. And for what it’s worth, I engaged in this kind of exercise only for them to nevertheless go ahead and buy the competing servos!

Recapping, looking into the Skywing 67in model is because I’m familiar with the class due to flying an Extreme Flight 69in Turbo Raven, which is about the same size. But I haven’t seen the Skywing Extra NG, much less flown it. So curious about it, my purpose in part was aimed at learning what others are experiencing with it. This, on the off chance it would influence how I was trying to help guide the guy.

TL;DR

Shortcutting the whole matchUP process, what I found out are servos suited for a EF Turbo Raven suit a Skywing Extra NG, also. And thus, killing Cock Robin, it’s my opinion (based on his response to questions regarding how he flew), that he did ‘not’ need such expensive servos as the Theta THM989 or MKS HV-747.

For his needs, I recommended the DS210CLHV – but he ignored me and ended up selecting our DS160CLHV minis – instead (but no extensions because they come preinstalled). He also ordered alloy servo arms, part number PDRS32-25T plus a B2S850 battery pack.

This last, a dedicated avionics power source, was a smart move in my judgement because in common with all models within this size range, the prospective owner is posed with the usual conundrum. You can either use the ‘free’ juice, which the BEC parasitizes from the propulsion pack at the expense of duration (so not actually free), or deal with the inconvenience of charging a dedicated avionics pack like either a B2S650 or maybe B2S850.

Thing about the BEC is beyond the flight duration this steals, then there’s also the non-zero risk of the ESC taking a crap. Problem is, when depending on the BEC-circuit to power the avionics, in the event of failure, this instantly converts you from pilot to crash spectator because you can’t just fly the now dead stick model to a landing. Really sucks!

Common? Nope! Rare? Not exactly – it happens – here’s proof.

Worst part is, this wasn’t some el cheapo import bundled with a motor to make a package deal but the best one America has to offer. However, and expressly because of how XA models are hammered, depending on a BEC stacks fire risk on top of the other risks. This is bad juju in my opinion, but it’s another decision you make, not me.

Fortunately, mitigating the risk is cheap and easy. Just use a lightweight dedicated 2S avionics pack. What’s more, I found it telling the fellow in question (despite dealing with a tight budget), gave it less than 2 seconds thought before opting for a pack.

Last thing before moving on, the DS160CLHV he decided on is one of three in a series we call the CLS-mini class outputting a nice range of torque for 60in models. They’re our best sellers (by a country mile).

So that said, because, a) everybody is different, and because, b) we have 3 other servos priced in the ballpark with the Theta THM989 and MKS HV747, and because, c) of what I ended up learning about both Theta THM989 (and already knew about the MKS HV747), then I’ve expanded on this TL;DR to offer a full-blown matchUP article.

So here goes, and offered in hopes it maybe helps guide you, also.

Background

To begin, there’s a lot to unpack in the few seemingly innocuous questions he put to me. Means this article runs a bit longer than usual because an investment in such expensive servos deserves our best effort at guiding you.

So there are lots of photos plus my usual long winded explanation of what you should be looking at within the various photos – and ‘why’.

If you’re short of time, the Page Down key is your friend because you may skip from picture-to-picture reading captions and also learn a great deal regarding these servos . . . but without all my wordiness!

So with the Theta THM989 mini servos in our hands, we took a slew of photos, which I’ll share as I explain what the important details are. And by the time we’re done you’ll be up to speed – and not just about these servos – but regarding what to look for in ‘any’ brand of servos.

This, because along the way you’ll learn a bit about what’s important in a servo (any and every servo) and also something about shortcuts, which some manufacturers may use to cut costs inside their product.

And ‘inside’ is the key because they all look ‘great’ from the outside!

Process

So my plan is to answer this in two parts ‘and’ in reverse order. The first part addressing the fellow’s last three questions, because they are so tightly intertwined I can’t realistically separate them out.

• What else have you got to look at? Several, 6 in total.
• Do I really need so much servo? Maybe, it depends.
• What else have you got less expensive? Four servos.

So to do this well, in the 1st part we’re going to examine several of our mini-class servo alternatives. Four costing less, one costing the same, and one costing an extra tenner.

And it’s in the 2nd part where we’ll delve into the heart of the matchUP. This is where we specifically respond to, ‘What I’m really wondering is what makes all these servos so God damned expensive?‘

In so doing, I’ll show servos ranging from $50-100, some of which may not only better suit him, but better meet your needs, also! And my reason for this approach is because above everything, the guy’s duty to himself (like yours to yourself) sees me responding to his real question . . . what’s in it for me? . . . e.g. in exchange for the dough.

After all, he kept circling around not just price and performance, but also whether he ‘needed’ so much servo (208oz-in to 320oz-in and priced at $90-100 per Extreme Flight’s offer). And ours, the one his pal recommended, outputs 405oz-in ‘but’ also costs $100 a pop.

Question is, who really ‘needs’ this much servo? Do you know?

Honestly? Some do, some don’t, so maybe I can help you suss it out.

So I’m thinking the old saw of a picture being worth a 1000 words may prove to be true for you (and me being ‘me’ means you also get the 1000 words). I’ll begin by offering up this photo as an example of what’s to come in the main event before getting to the article’s meat.

Disclosure

And by way of heads up, everything that follows is 100% my opinion, and yet, because of the photos, it also means you don’t need to be an engineer to judge these things for yourself. Why not? Simple, because you get to use your own eyeballs to judge my word’s weight.

And I’ll start off by admitting I’d never heard of Theta, but overnight they have made an explosive entrance into the market. They offer a full line up of servos that rivals our own (yet which took +10 years to grow one servo at a time). How can this be?

Honestly? I have no clue. I suspect these are just another of many east Asian imports looking for a piece of the lucrative American servo market. That said, and in further honesty, this is a nicer looking servo than ours, which many, many, many have told us are plain looking.

Like the secondary operation (after anodizing) to reveal the alloy is reminiscent of fine quality camera equipment, isn’t it? Just beautiful.

Part 1: less costly alternatives

So because of my plan to address his concerns in reverse order, then we’ll begin by teeing up, What else have you got to look at? Do I really need so much servo? What else have you got less expensive?

To the first and third question; ProModeler have several mini-class servos, but first, the basic specs of the EF recommended servos are;

• THM989 – 320oz-in @ 0.07sec/60° – $90
• MKS HV747 – 208oz-in @ 0.13sec/60° – $100

And we’re going to touch on six ProModeler servos, which include;

• DS110CLHV – 110oz-in @ 0.035sec/60° – $50
• DS160CLHV – 160oz-in @ 0.06sec/60° – $60
• DS210CLHV – 210oz-in @ 0.06sec/60° – $70
• DS205BLHV – 205oz-in @ 0.052sec/60° – $80
• DS355CLHV – 355oz-in @ 0.08sec/60° – $90
• DS405BLHV – 405oz-in @ 0.055sec/60° – $100

And of these, two make less torque, two make more torque, all but one are faster, and four of the six cost less. Are any of these the best servo in the world for the Skywing 69in Extra NG? Maybe. Let’s see!

Birdwalk – wingspan vs propulsion

So before we even get going, we already have a brief birdwalk. This, because as it turns out, mini class servos for this class of models aren’t so much bound together by wingspan as by propulsion packages. I’m going somewhere with this as we have to try and help him (and you) figure out if you even need +300oz-in servos.

Some do, some don’t, and as usual, it depends! On what? On you! And simply reviewing a few caseSTUDY articles proves the point;

• Extreme Flight 69in Turbo Raven servos
• Extreme Flight 84in Turbo Bushmaster
• 60-class servos
• AJ Models 62in Acuity servos

. . . because all use mini-class servos despite a considerable range of wingspans. E.g. all rely on 6S power packages, with all also swinging props in the range of 16-17″ diameter. Wingspan just doesn’t factor.

In a nutshell, what actually defines this class of model in my opinion are commonality of propulsion and purpose, meant for XA-type aerobatics. This means what works servo-wise for the above models, may also work perfectly well for the 67″ Skywing Extra NG. I think this helps as the experience of many others will guide us.

ProModeler lineup of mini-class servos – from 110oz-in to 405oz-in.

What’s more, we feel the our broad range of minis – expressly because they encompass a wide coverage of prices from $50-100, with all using steel gears, and offering MIL-STDS, plus a center case CNC-machined as a heat-sink due to cooling fins, plus bronze or steel bushing reinforcements within the case – represent to your wallet, the ‘best’ possible bang for the buck on the planet.

Big words? Maybe. Thinking before we’re done we’ll show you something that’ll prove it for ‘your’ special use-case, and budget. To the question; Do I really need so much servo? It really depends on you, so next I’m going to try and help you figure this out.

And FYI, when speaking with folks, first question out of my mouth is, how do you fly? Reason I ask is there are typically 3 classes of pilots for this type of model.

The answer helps in guiding someone to how much servo is needed!

Pilots

It’s our experience, there are three basic types of pilots for models of the type sold as XA (with XA being defined as extreme aerobatics).

Thing is, just because a Skywing Extra NG is like a katana in the hands of a samurai warrior doesn’t mean everybody wields it as such. Some folk just love the look and only want the model for fun.

So while flying one of these just for fun is doable, it means we’re going to touch on setup, also. This because if you look carefully, these things have wicked large control surfaces. Like 60% of the stab is elevator and 40% of the wing surface area is aileron – that’s a lot!

Sport models, by way of comparison, may have 25% elevator and 15% aileron. Big difference. Means if you setup for 3D maneuvers but you’re a sport pilot, then you’re apt to crash on the first flight. Why?

It’s because it’ll be, a) too tail heavy for you to handle, and b) have throws so extreme (for post-stall maneuvering), that you’ll overcontrol it from the get-go (maybe resulting in a first flight crash).

Setup involves servo arms, throw, and balance – you’ve been warned!

Birdwalk – servo arms

So here we are, already our second birdwalk! Can’t be helped because while there’s an infinite number of pilots, if we slice and dice to put them in 3 buckets, they’re club pilot, hotshot, and hooligan.

Thing is, the length of the servo arms for a sportsman and those for a hooligan are two vastly different things. So is balance. What are the usual words out of the mouths of the inexperienced are, I want to long arms for a hooligan setup and I’ll dial back the throws with the radio.

That this doesn’t address the aft balance point of a pro goes right past them. Know what else does? That while this sort of works, it also throws away the system’s resolution, resulting in inferior precision for IMAC-type maneuvers.

So you may think you can set up for 3D and IMAC, but it’s a fools errand. Why? For the same reason the Bible in Matthew 6:24-26 says . . . ‘No one can serve two masters.’

Point being, after paying a butt load for a high performance model and more for premium equipment, then it’s tossed because you think you know more than dedicated IMAC and XA-pilots? Seriously, like how stupid can you be?

The right way is to shorten linkages and increase ATV (versus dialing it back out because of long ass linkages). You have to be strategic!

Anyway, if you buy their PNP version you get the servo arms they include, which are 1.25″ long (aka 1-1/4″, or 32mm). And while these are perfect for the samurai, they’re waaaay too long for the sportsman because they result in the extreme throws.

So 1.25″ are are long to get the throw to permit post flight stall maneuvering, but this also renders the model essentially uncontrollable flight for the novice, sportsman, and many club pilots.

This is why their servo arms have 3 mounting positions, and the smart club pilot uses the inner holes, else they’ll have a handful on that first flight! So are three positions good enough? Yes, likely so.

So each pilot type, and for their own individual reasons to do with skills, desire, and budget, makes decision regarding the right servo and the right servo arms. We offer servo arms, also.

For example, ours include a range some may find useful to to theirs. The middle one, PDRS32-25T is also 1-1/4″ or 1.25″ long. And instead of 3, it has 6 mounting positions. This allows more refinement in the setup.

Maybe this is important for you, maybe you don’t care, dunno. I mention it for just in case. Note; we offer the longer and shorter alternatives for if you’re a fierce wildman, or more IMAC oriented.

So visit out site and wonder, why do you offer so darned many arms? And FYI, the count is up to 52 as of 2024. Simple, for the same reason Extreme Flight offer so many specialized XA-type models.

We each, respectively, do it to better serve you, our customers! Life for us, knowing servos like we do it means instead of using 6061-T6 we opt for 7075-T6 because the yield strength exceeds some mild steels.

And while hobby grade arms rely on flat profile we use an H-beam profile, instead (think I-beam but sideways). Plus the arms are a bit thicker to ensure more threads are engaged. This, because we detest feeling like having to add a nut to the bottom of the bolt securing the ball. Oh, and we don’t do colors. Nope, not into that.

So doesn’t it also stand to reason someone focused on the needs of the samurai-type pilot may overlook the grasshopper when it comes to servo arms? Maybe. Our focus is solving problems for all pilots!

Thoughts on guidance

Anyway, guiding you would be a lot easier if we were club mates.

Like if I knew how you fly ‘because’ we flew together, then I could maybe bluntly say, ‘You’re never going to perform a crankshaft, so forking over $100 for DS405 servos is stupid because the only place you’ll feel a difference – ever – is in your wallet!’

Or maybe, ‘I’ve only seen you fly inverted on purpose once, and I could hear your knees knocking, so trust me when I say, those $50 ProModeler servos are plenty good enough for maneuvers you fly.’

Another thing a real mate could say is, ‘You have a kid on the way, chum, even a new model is a stretch but $90 a pop for servos, like right now? That’s crazy, man, to the $60 servos, instead!’

However, we’re not mates, so hard truths can’t come from me. Especially when not actually knowing you also means I don’t know your circumstances while I’m making suggestions. So my best advice is remember what we learned from reading Hamlet in high school when Shakespeare wrote . . . ‘to thine own self be true.’

This is the best I can do trying to help put yourself into the right frame of mind both performance and budget-wise more clearly. So next, let’s try and figure out who needs to spend how much for servos based on who they are, their skill-set, and their budget

Club and sport pilot

The club and sport pilot are referred to as gentleman fliers. These include the novice getting into 3D because he’s a reasonably proficient pilot, else he doesn’t begin that regimen of flight, capisci?

All pilots fit the description of ‘club pilot’ and they encompass a wide range of flying skills ranging from beginer XA-pilot to proficient ones. And all, perhaps to do with budget, or uncertainty whether they really have a serious interest in XA, many aren’t eager to pony up for $90-100 servos. Basically, it’s because they’re in it for fun!

For these folks, equipping a 67″ wingspan model, maybe because they don’t fly especially hard, or are on a tight budget, means I’d guide them into either of 2 minis – priced $50 and $60 respectively;

• DS110CLHV – 110oz-in @ 0.35sec/60°
• DS160CLHV – 160oz-in @ 0.06sec/°

Budget alone shouldn’t make the final determination. There’s a nearly 50% bump in torque between 110oz-in and 160oz-in for an extra tenner. This becomes an important consideration, not so much with the low-and-slow stuff but when maneuvers become more violent. So when choosing wisely, know when the smart thing to do is wait and maybe save for one more paycheck before plunking down the charge card, right?

Other valid considerations for not buying 300oz-in servos include not getting the opportunity to fly as often, hence never making great strides as an XA pilot because you’re also not the type to spend 2 hours a night after work on the simulator (those guys that are good devote enormous amounts of time getting there, they may have God given talents and the reflexes of cat but it still takes a lot of practice).

Or maybe you’re just more into the whole low-and-slow scene (meaning lower torque requirements on the servo due to reduced airspeed). Kind of pointless ponying up big money for more powerful servos if you’re never going to use them, take my meaning?

So if you do Harriers and hover but never do crankshafts or Walls, then you don’t need more than the DS110 servos. And ‘this’ is what I mean about you have to know yourself!

Another thing the DS110 brings to the game is it’s stupid fast. By comparison, it’s transiting 60° in 0.035sec vs 0.07sec for the Theta THM989, which is exactly 100% slower.

That, and some folks love what gyros bring to the game (speaking of low-and-slow guys, principally) so if you have a fine appreciation of what a gyro brings to the game (and gyros LOVE speedy servos) and if at the same time, you’re more into IMAC stuff, then it’s plain silly to pay nearly twice as much for 3X more torque you’ll never use. Especially when it means giving up the benefits of really quick servos, also! See what I mean when I say . . . it depends?

So while all of these pilots can control the model really well, maneuver and land with never any risk to the model of crashing because they dumb-thumbed it, or maybe because they’re not into ‘hard’ maneuvers, then they don’t want to pay a butt load for their servos!

Makes DS110CLHV and DS160CLHV quite reasonable alternatives.

Thus, depending on how they fly, like if your interest is more into IMAC maneuvers, then 110oz-in is enough torque. And because the DS110, DS160, and DS210 share a frame, then owning the DS110 means enjoying the fantastic durability that comes of it being built same as our 210oz-in (because these CLS-minis are as alike as three peas in a pod). With all three being built with the goodness of a genuinely lightweight case going just 39g vs 54g (15×6=60g.

I mention it for if you’re one of those for whom weight really matters.

Then for example, on another end of the scale are club pilots who fly a lot. They go to the field two maybe three times a week and put five, maybe six packs through the aircraft in a day.

What’s more, they know everybody, everybody knows them, and they’re totally solid pilots who perform torque rolls, and hover with the best and thus, appreciate good centering and fine quality.

But maybe they also have to watch the bottom line. Means top of the range servos are a ‘some day’ purchase and in the meantime, they go for a more budget friendly alternative like our DS160CLHV servos.

However, all pilots get tremendous benefits in selecting DS110 or DS160 servos – like increased durability. For example, when your servos are working hard, because the motor is a press fit into a heat sink center case, it sheds heat better.

Smooth case alternatives like THM989 and HV747 (due to lack of cooling fins CNC-machined into the sides), simply can’t shed the heat as quickly and efficiently. This isn’t my ‘opinion’, it’s physics!

And to some of you, these are the kinds of details that matter!

So for those for whom almost $500 for an ARF is a lot of dough, especially when considering the addition of another $400 for servos and arms, then they could do a heck of a lot worse than our DS110 or DS160 CLS-class mini servos.

In fact, I’ll go out on a limb and say . . . for 80% of you reading this, the DS160CLHV – at $60 a pop – are the right servo for you.

Look, these DS110 and DS160 servos represent something of a bargain in the way of price vs. performance. And seriously, these days, who can blame ‘anybody’ for being careful with a buck?

So if any of the above describes you in some ways, then we offer you two alternatives (for substantially less than tearing up a bill) where one or the other may well be a better servo for you and your needs.

MIL-STD

Most especially when you consider something else you get with your CLS-series minis, which imports don’t give you . . . MIL-STDS.

One place where it’s easy to see the MIL-STDS is our liberal application of potting compound to the printed circuit board. The use of potting compound is a full-scale aviation technique our principal customer insists on (else we don’t get the contracts).

So here’s how this plays out. As a consequence of their influence on us, then ‘you’ benefit if for no other reason than there are plenty of cheaply made imports available, so a) the market doesn’t need another player, and b) it’s just not who we are.

What it boils down to is building a budget line isn’t compatible with our goals because instead of fretting about how to make something more cheaply, we’re all about trying to come up with how to improve on something. Like where even 1% is a big deal. Prove it?

OK, by way of comparison, this next photo is the Theta THM989 PCB, which also has some potting compound. So ask yourself one simple question, does this look like it meets ProModeler standards?

Way we figure it, once you taste the good stuff you’ll never want to go back. So either our competitors up their game, or we’ll keep eating their lunch because modelers, aren’t stupid. Like who willingly settles for second best? Especially when the best is priced pretty much the same as everybody else.

So next, let’s see how it’s ProModeler establishing the benchmarks. In those previous photos, you saw what to expect in the way of a good application of potting compound vs what we compete with and in this next photo we’ll show you why it matters.

Note how the microprocessor in this photo vibrated off the PCB.

So once the solder legs holding the microprocessor broke, instantly it became a dead servo. What’s interesting is we soldered the microprocessor back in place and presto, the servo still worked! But the application of potting compound would have prevented this in the first place!

By the way, potting compound is applied as a liquid. It stinks, and it’s sticky as Hell. We call it monkey snot. But once it flows in and amongst the various surface mount components and sets up, then it reinforces the components like diodes, and FETs.

This is basically how you earn test methods 516.6 and 514.6

Of course, repairing a servo isn’t exactly a viable option during the mission, hence our heavy application of potting compound as a preventative!

And FYI, the expensive part isn’t actually the monkey snot itself, but the time it takes to apply ‘and’ wait before assembly. Worse, it’s not just one side of the PCB, but the other, also! Yet what’s the alternative? Don’t use it, or be so parsimonious in application you may as well have used none?

Anyway, ‘this’ business of the using potting compound is one of the things where by just using your eyes, you can immediately distinguish products where your standards are being upheld.

After all, your money, which would you prefer? We learned this the hard way when we first began discovering how to earn the MIL-STDS for shock and vibration. We’re never going back!

Next, eyeball the electronic covers. The one for the THM989 is plastic like the one for a CLS-mini. It’s OK to reduce weight and save money but alloy is better for cooling. We use plastic, also but once we get into serious servos, we switch to alloy.

And, take note of the o-ring around the electronics cover in this last photo. When you pony up for ProModeler CLS-mini servos, they have 13 individual seals and o-rings protecting your investment against environmental intrusion like dust, humidity, sand, and water.

To some this matters, others don’t care. You get the benefit, anyway.

Hotshot pilot

Next, there’s an in-between type of pilot. Talking about ones with solid technical skills. These guys can hover and perform torque rolls. They fly harder than most club pilots and appreciate more powerful servos. So now our recommended range goes up to 205oz-in through 210oz-in. More torque is useful when flying harder!

• DS205BLHV – 205oz-in @ 0.052sec/60° – $80
• DS201CLHV – 210oz-in @ 0.06sec/60° – $70

We’re also talking about the über competent sticks who attend a lot of events, fly a lot, and for whom centering is supremely important. They are folks who can competently perform 3-rolls down low (with low being defined as <10 feet) who love to showoffs for the crowd because they’re damned good and love a spot of fun.

What’s more, they’re such good a stick they’re the guy often called upon to do the majority of test flights for other club members. Quite honestly? These are the guys are at the top end of the pilot skill set.

Interestingly, someone says they’re into 3D and IMAC, then you’d better believe I know I’m dealing with someone totally into performing maneuvers smoothly and occasionally letting the wild side hang out.

Think competitive types whose repertoire of maneuvers includes credibly performing many if not all from the old FAI schedule. And then letting it rip with rifle rolls where instead of 3-rolls, you get 15!

Birdwalk – heat

For pilots who fly harder than the average club pilot, it also means the servos are working harder. Harder working servos means hotter. Why? Higher current consumption because you don’t make power out of thin air. Proof?

Simple, just eyeball the specification chart for your next servo purchase. Do it in advance so you know what you’re dealing with.

So with hobby grade servos finding this depth of information is basically impossible. Things sell based on pretty pictures and basic specs like torque and speed. But the technical details? Forget it.

With ProModeler, instead of hobby grade you’re buying servos meeting MIL-STDS where primary clients are project engineers. Sure, the savvy hobbyists buy them too, but our principal customers are the engineers. And instead of bullshit, engineers thrive on data.

Like what’s the gear ratio? It’s half way down the technical block on the right side. Look where it says Material/Ratio and the answer for the DS210CLHV is All-steel/290:1 and presto, the data they need all without them having to waste time picking up the phone and calling.

Or maybe they need to know how many, and what grade, bearings are use; 2X (ABEC-9) is the answer. O-rings Seals? 13X (Buna-N). How about Wire/jacket? 22ga/PVC is the answer. We don’t hide this stuff from you.

How do you find this kind of data for imported hobby grade products? I couldn’t tell you. Do know this, when serious people have questions, last thing they want to deal with is someone just selling stuff who hasn’t a clue.

So back to heat (what started this birdwalk), harder working servos get hotter. Proof? Simple, physics! Solving for P=V*I has the answer. Yup, the good old power formula.

Heat and current consumption

So input V (volts) and A (amps) and solve for watts (W). Pick these values off the above spec sheet and let’s say you favor A123 packs. Since they’re done at 6.6V, that’s the worst case for the pack. Find that in the middle column, and note it’s also pulling 2.8A when stalled (this is when the servo actually makes rated power).

So plugging in the numbers as we learned in 7th grade math and we have P=6.6*2.8 and the answer is 18.48W. Ever touch a 15W light bulb when it was too hot to unscrew but you were in a hurry? Burnt the crap out of you right?

So these are basically 15-25W devices (an A123 outputs ~8.1V when fresh off charge so the numbers then work out to 8.1*3.2=26W). This class of servo consumes a fair bit of current and produces heat as a byproduct. Can’t be helped. So how do you deal with the heat? Best way is using a heat sink to shed it more quickly into the air.

So here’s the thing, every single ProModeler servo, whether it’s an entry level model costing $30 through $500 units, makes the center case function as a heat sink. Just like an F1 car uses the transmission as a structural member, thus performing double duty, at ProModeler, the case isn’t just the foundation to which the transmission, motor, and potentiometer are attached. It’s also got the added function of working as a heat sink to shed excess heat.

True for every single ProModeler servo!

Why? Because we take the time to CNC-machine them with cooling fins. And because we use ten bolts in their assembly instead of just four, they’re nicknamed the porcupine section, can you figure out why?

How about hobby grade products? Honestly? They largely pay lip service to cooling. And the reason they can get away with doing it this way with modelers is because their duty cycle is very light. In hobby duty, e.g. for flying model, the cycle lasts maybe 4-10 minutes/flight.

Conversely, ProModeler servos undertake missions lasting hours! So we have to be serious about shedding heat since crapping out an hour into a 6 hour mission isn’t acceptable. Maybe you don’t need this level of service but ProModeler servos are made to handle it.

Note, when hobby grade products do use an alloy case, they’re typically smooth sided, or have fins in name only = like they’re really just decorative. Why? Simple, money!

It’s because the time required to CNC-machine the fins basically doubles the cost to make the part. It starts with doubling the time within the machine cells due to the added time to do the job. This, because the feed and speed is slower since it’s cosmetic.

Added to which, because the working stiff manning the machine waits twice as long, and because he’s paid by the hour, then each parts just cost more money. Simple math.

Now I promise you, doubling the price of a part is NOT what someone importing el cheapo servos wants to deal with. Instead, they want to promote and advertise their way to a fortune as quickly and easily as possible. How?

Typical tactics in the hobby business are as familiar as they are in NASCAR. E.g. sign a big name pilot, emblazon their good name on the product, and shovel it out the door as quickly and cheaply as possible. That’s the business model often used not just in the sport of RC, but in many others forms of consumer sales. Why? Because it works.

It’s just not the ProModeler approach. Our pilots? 100% are sponsored by MasterCard. Team pilots? Don’t have any. Field Reps? Ditto, we have none of those either.

Anyway, back to the lack of cooling fins; it’s our theory this is because engineering take their marching order from sales, unlike with ProModeler where engineering runs the show. So sales they tell engineering, ‘Screw the cooling fins!’ we want this made as cheaply as possible so we can make as much money off rubes who buy on the basis of what’s hot on the forums.

It’s likely exactly how you get servos without cooling fins. Supposition? Yes! But I promise you this, engineers in China know better (they’re very smart, hard working and definitely not stupid). Meanwhile, we can’t come up with any other explanation for why cooling surface area is dedicated to logos and propaganda instead of cooling fins.

IMAC and hooligan pilots

Finally we have the guys who are perfectly happy to pony up $100 for servos. They know what they want and are willing to pay for it. There are typically two types of pilots in this group.

First, there’s the highly disciplined guy who practices several times a week. Then he goes on the contest trail. Talking about the guy seriously into IMAC competition.

Second, there’s the guy who flies it like he stole it. His flight is 6 minutes of crankshafts, rifle rolls, Harrier rolls, hitting the Wall so hard it seems miraculous the model doesn’t disintegrate in the air.

Is this you? If so, then you’re our natural customer.

Birdwalk – CLS-mini gear train

Why do I suggest you’re our natural customer? Simple, because of how our servos are build on the inside. Ever noticed, the inside is what the hobby grade vendors never show you?

So here’s the deal, just like two models weighing 5 lbs, one with 500in² of wing and the other with 750in², fly vastly different because the latter has a much lower wing loading, in the world of machine design there’s a similar concept called pressure loading. And if you take two gears – experiencing the exact same load – the smaller has a higher pressure loading.

And just as with a model, where a lower wing loading means desirable flight characteristics, with machine design, it’s the same. But with a lower pressure loading on gears, for example, it means they last longer and can be run faster and harder.

Heck, this stands to reason even without an engineering degree! So now let’s eyeball the output gears of the $90 Theta THM989 against the gears of a DS110/160/210 CLS-mini from ProModeler going $50/60/70 a pop. Trust your eyes!

Where’s the beef?

So in the above close up photo, on the left is an output gear made of 303 stainless steel. It’s sized and designed for a long working life by ProModeler engineers expressly to handle 210oz-in. It’ll handle this for years if not decades of use. Honestly? It’ll handle a lot more!

One the right is one also made of steel (nickle, or maybe chrome plated – no available specs to find out). It’s sold in a servo rated at 320oz-in, which is a 52% higher load than that at which the ProModeler is rated. Yet the gear is a lot thinner. Will it handle this load? Oh yes, definitely! No question about that. And proof is, it does!

Doesn’t mean there are no questions. Like one important one is, for how long will it handle the load? Being thinner you better believe it’ll wear faster just because ounce-for-ounce, smaller means a higher pressure loading on the wear surface. Added to which, how well does will it stand up to the shock of impact, e.g. a crash?

Do you know how gears actually work? They slide one involute face against another involute shape face! Pressure loading is real because the surface are is what determines things.

It’s measured in psi (pounds per in²).

So it’s our opinion, during the same crash, the ProModeler gears will handle it better because they’re bigger. Stands to reason. And yes, this is an educated opinion, but we say this due to it being so much thicker, or wider! Much more area. So same impact presents a lower unit load. And we know 303 stainless is the good stuff vs. an unknown grade of steel.

So let’s take some basic dimensions and see what we’re dealing with.

Heck, even without a college degree in engineering you know the pressure loading’s higher at the same loading because the gear’s so much thinner.

So let’s run some numbers and see what we actually have. As measured (above) the THM989 output gear are 0.080 inches thick. What about the ProModeler (note, we’re measuring the gears of a DS110 but the DS160 and DS210 use the same basic gear sets, just different ratios, so strength due to the same thickness is the same).

These measure 0.2125 inches thick, so double theirs, 100% wider is 0.080*2=0.160inches. Ours is wider, still. Not quite three times wider (0.240) but it is 165% wider.

That’s a lot more. You might say . . . there’s the beef! So now we have another question for you, when talking about roughly the same class of money, which gears do you prefer?

What else distinguishes a servo built to the ProModeler standard?

Case construction

The THM989 has an alloy case. The ProModeler uses a hybrid (alloy plus plastic or polymer). Their all aluminum case is better, right? Not so quick! Let’s delve deeper. For starters, it’s not all aluminum. Anyway, for this conversation we need to field strip the servos down a bit. Let’s remove the gears and see what we have.

What’s important to take note of the THM989 is heavier (54g) but not as durable as the lightweight ProModeler polymer case. Why is this?

It’s because they fit the gear shafts directly into aluminum, which is soft. Conversely, the lightweight ProModeler (39g) has gear shafts fitted into hard brass bushings. Where the steel shafts will oval the aluminum, the brass laughs at it!

But there’s more.

Not only is the THM989 heavier but the gear shafts are smaller in diameter. Go figure.

And a smaller diameter shaft, much like a sharper knife imposes a harder force against the aluminum. And brass is a LOT harder than aluminum, which is why we use it. Let’s see what we’re talking about.

The THM989 gear shaft diameter is 0.059 inches.

And when we measure the same way, using a fine quality precision micrometer, the ProModeler CLS-series gear shaft measures 0.062 inches.

And this works out to a touch over 5% larger in diameter. While this doesn’t sound like much, this little bit makes it a lot stronger because these shafts are very short.

The killer is when we look at the upper case, the transmission cover. Once again, the shafts set directly in soft aluminum versus hard brass bushings.

CLS-series summary

Anyway, if you can live with 2/3 the torque, the Theta THM989 with 320oz-in versus the DS210 with 210oz-in, you get much bigger and stronger gears, larger diameter gear shafts, much more potting compound (and the TMH989 transits 15% slower at 0.06sec/60° vs 0.07sec/60°), plus with ProModeler, the foundation, the center case does double duty and has cooling fins so it functions as a heat sink.

And if you can stand the extra tenner, the DS205BLHV is 30% quicker which means a lot when you’re expecting the control surfaces to shift from 45° in one direction to 45° in the other in the blink of an eye!

Part 2: Main event – matchUP

So for the guy who is an utter natural on the sticks, we’re talking about guys blessed by God himself with a talent that brings the show to a stop whenever they take to the sky, this is for you.

You know who I mean, the ones for whom folks stop flying just to watch as they performs crankshafts, rifle rolls, and wall maneuvers. Plus Harrier rolls within ten feet of the ground the length of the field!

And no, these guys didn’t get there without practice, just that they make it look easy.

Background

To begin, and in full disclosure, in our testing the THM989 proved to be not just very handsome, but performance-wise, it’s both smooth, powerful, and meets the specs.

In further honesty? We can readily see why it’s popular. Priced at $90, it represents fair value to many modelers, else Extreme Flight don’t bundle them with their RC Skywing brand of models. Nor do they succeed to the spectacular extent to which have within such a short time frame.

Against it we offer the ProModeler DS355CLHV for the same $90 and which, for the weight conscious goes 44g vs 54g and DS405BLHV (54g vs 54g), and which for the extra $10 is priced against the better made MKS HV747 that’s way down torque-wise, and as my potential customer observed, these things are expensive!

Question is, why? And is it worth it? Since that’s the point of a these matchUP articles, let’s find out . . . together!

Considerations

Of course, it stands to reason ‘we’ feel we’re offering you a better servo, else what are we doing in this business in the first place? However, while we believe the DS405BLHV is easily worth the extra $10, it’s not really on us to decide.

That’s your call and since neither the Theta THM989 or the DS405 are exactly cheap, let me first state, thanks for even giving us a shot at earning your business! We’re going to proceed quickly principally using photos to tell the story because from reading the above, you already know what to look for in an actual top quality product.

On the electronics side, both use brushless motors. These cost more. They’re better. And in our opinion, worth the extra dough. Don’t know diddly about this? Read up with this article;

• About RC servo motors

Basically, this article can be summed up with this graphic.

So these servos are superficially similar. Both fit in a mini-application, the THM989 outputs 320oz-in while the DS405BLHV does 405oz-in, or 26% more. And at 0.05sec/60° vs 0.08sec/60° theirs is considerably slower (60%), which for IMAC doesn’t matter, but for the XA-types is a really big deal.

Means you have to know yourself.

Speed

On the basis of raw performance, if the torque difference doesn’t matter because you don’t fly hard enough to appreciate it, we feel the increased speed alone justifies the extra $10 even. True even if their build quality were similar. However, we don’t feel it’s in our same league. And before taking offense, remember, it’s our opinion, which like belly buttons we all have. What matters is your opinion!

Since you’re still forming yours, then let’s move on and see what there is to see inside the products, because knowing this informs our opinion (and may shape yours, too, once you know what we do).

As a reminder, these are the servos in the main event.

Potting compound

So next, let’s look at potting compound again, same deal as with the CLS-series – like what else can we say? We’re certainly not changing our thinking on the value of protecting your investment.

For your part, it’s your money and either this matters, or it doesn’t.

Fasteners

What else is there? ProModeler rely on ten stainless steel Allen head bolts to secure the assembly instead of four long black oxide bolts. The stainless resists corrosion better.

But there’s more to the story.

Rigidity

Reason for using 6 bolts to secure the upper transmission section to the foundation element, the porcupine center, instead of four is to increase rigidity. The extra 2 bolts box the output shaft bearing.

The entire purpose for this is to make the assembly more rigid where the shaft extends beyond the case. Basically, it reduced flexing under heavy load.

No, this doesn’t matter in the slightest with low stress aerobatic, e.g. low-and-slow, but it matters a lot at 80mph when you jam a big ass aileron out in the breeze to 45°. You know, to perform harsh maneuvers like rifle rolls. Ditto crankshaft or Wall maneuvers that will strain the crap out of everything.

Electronics cover

Note also, the electronics cover is plastic instead of alloy with the THM989, but aluminum helps shed more heat. Reason is, at these kinds of torque output levels and transit speeds, the servos really become systems.

This means every components plays added roles. So working together as a team means the alloy electronics is ‘also’ used for shedding heat. And once again, this is big time important.

The importance of shedding excess heat toward improving the lifespan of the electronics cannot be overstated.

Lead

This next detail will seem like a small thing, and it is, but we’re using 22AWG while they’re using 26AWG leads. Theirs is 12in to ours 11in.

An extra inch sounds handy until, a) you consider you’re almost to a certainty going to use an extension, anyway, and b) the smart money sees you connecting to a 20AWG extension (thicker), which results in less voltage loss at the servo.

Don’t know abut this stuff? You’re not alone, which is why you can bone up by reviewing this:

• Servo Leads & Extensions

Bottom line? Shorter and thicker leads are actually better!

Does this business with the leads seem trite, like a trivial detail? Yes, but once again, we’re dealing with a system where everything works together. So in order to output more torque we need to make more current available to feed the motor. Means thicker wires are used for a reason.

So in order to output significantly more torque ‘and’ do it whilst delivering the torque with quicker transit times than the THM989 means every single detail counts no matter how small.

Honestly? Nothing is insignificant when we’re chasing your money, or are we mistaken in trying to do our best?

Bushings

So these stainless steel bushings are knurled to help anchor them into the alloy. We don’t make them and instead, a pal with Swiss lathes turns them for us (hard to beat a man a this own craft). And we buy the tiny buggers in quantities of a quarter million at a time else they cost too much!

Remember, the gear shaft takes a beating each time you deflect a control surface out in the breeze at high speed. Yes, I’m going to keep harping on our using bushings for reinforcing the soft aluminum alloy because it’s a big deal.

Cooling fins

Anyway, the purpose of this next photo is to show off the bushing, not to dramatize the cooling fins, or more accurate, the lack of cooling fin on the THM989 case.

Why such a hard on with regard to bushings? Simple, cumulative time at high pressure loading leads the normally round bore to become an oval. It happens because the small diameter steel shaft is a lot harder than the soft aluminum.

So once the bore becomes an oval, then it doesn’t take an engineer to realize any semblance of precision within the geartrain is gone. Zip, zero. This, because the precisely located shaft is no longer at the design point.

Gears – again

So what this means is gear mesh goes to hell, thus leading to accelerated gear wear. And it’s at that point that all bets are off.

Especially once you look more critically at the comparative size of the respective gear trains.

Birdwalk – DS355CLHV low-profile mini

So now let’s turn our focus to another mini in our line up. One we’ve been ignoring, the DS355CLHV low-profile. Turns out in terms of performance they’re close to a wash. Price-wise, at $90 each they’re also tied. Let’s delve deeper.

So at 44g vs 54g the THM989 weighs 22% more than a DS355CLHV. And yet, despite weighing less, the DS355 makes 11% more torque (320oz-in vs 355oz-in). Transit time is a tie at 0.08sec/60° for each.

And it weighs less despite the DS355CLHV output gear that positively dwarfs that of the THM989 whose gear thickness, at 0.059in vs 0.188in thick.

This makes the DS355 gear 218% thicker (so more than twice as thick). This matters during operation as it’s a proxy for lifespan, and while we don’t plan for this next thing, it matters in a crash because thicker gears are just more durable.

Again, not to harp but it’s your money and these details count, right?

So how can the servo be lower in profile and at the same time weight less, and yet we manage to stuff it full of larger gears inside? Magic!

I know it may seem like it but this has to do with our borrowing a design element from our BLS2 series, the 5-shaft gear layout. So while it may seems a lot like magic, our design engineer (that would be moi) resorted to the 5-shaft bag of tricks. This is the DS635BLHV from which I modeled the DS355 gear layout.

The DS355 uses the same layout of our BLS2 super series standard class servos. It’s a design package that allows us to craft the low-profile DS355CLHV mini, a servo weighing a mere 44g yet outputting it sees it outputting 355oz-in and transiting in 0.08sec/60° – yeehaw!

Gear wear, or why size matters

So here’s why we use larger gears when we know we could use smaller ones to save money. It’s because smaller gears experience higher pressure loads. Means higher rates of wear. And no matter what someone may think, this is not my opinion . . . it’s physics.

So thicker gears aren’t just stronger in a crash, they’re more durable, also. Means once the gears ‘do’ begin to wear, backlash increases rapidly. And there’s not a pilot on the planet likes excessive backlash.

There’s only the only fix . . . new gears. But there’s a rub. If the case is worn (or damaged in a crash), then a new set of gears won’t do squat to help you because they’ll just begin to wear quickly, again.

So then the real solution becomes a new case. And circling back to my opinion, it’s all because the THM989 doesn’t have bushings reinforcing the soft aluminum of the case. The bushing almost to a certainty would preclude wear and the damage from crash impact. Wear that never begins in the first place due to the bushings!

On the flip side, THM989 gears ‘are’ inexpensive, like $15 vs $35 but you’d be wise to also price a new case. No clue if they sell these because we looked and found no product listing anywhere for a replacement.

So here’s the thing, if you can’t buy a case, then does it make sense to replace gears even if they’re dirt cheap? Saying from the view of the customer, the THM989 then kind of looks like it’s may be a one and done kind of product ‘if’ the case suffers damage. Like repair really entails buying a new one.

So where’s the economy in that?

Upper case bushings

Care to take a guess what I want you to observe next? Yup, bushings in the upper case, also. So with the DS405, once again steel, and pressed into the soft alloy to reinforce where the gear shafts are fitted versus nothing at all . . . just soft alloy within the Theta product.

So this Theta servo has bupkis in the way of case reinforcement. And for a product outputting +300oz-in and going for $90, there are some who view it as a dubious value proposition.

Like there’s a good reason we reinforce ProModeler cases. We certainly don’t do it for our health. Instead, we do it so your hard earned money pays for a product that will last, and last. Some folks don’t care about this because they don;t fly hard. Our point is you pay about the same, anyway so why give it up?

Whatever, none of our business. Yours, and yours alone.

Value – or why so expensive?

So let’s wrap this up. Let’s look at why servos cost $90-100. And once we suss this out, we’ll have put a bow on things. So to figure this out, we actually need to work the numbers backwards.

Chain of distribution

The hobby product distribution system in the United States depends on several players. It’s sometimes referred to as a chain because each player is a link.

Way it works is there’s the guy who imports the product. Of course, he gets a cut, duh! The distributor is next, this is the guy with the keys to the kingdom (keys defined as +1000 hobby shops on tap). So obviously, he gets a cut, also. Then there’s the hobby dealer himself, e.g. HobbyTownUSA, Joe’s RC Hobby, or in this case, the guys packaging servos with their product, e.g. Extreme Flight offering a bundle of their fabulous model with Theta THM989 servos.

So let’s put numbers to this and remember, everybody has to eat. Taking a $90 product and working backwards, the hobby dealer usually works with a 40% margin. Think he’s fucking you?

Nope, find me a hobby shop owner whose wife drives a Cadillac and you’ll understand when I say, the hobby dealer makes the most but needs the most else he can’t make the nut. E.g. rent, light bill, insurance, taxes, employees, himself, etc. So his 40% cut works out to $90*0.6=$54 – so he pays $54 for the servo costing you $90.

Who’s next? The distributor. And in America the system is dominated by a few big guys. Outfits like Ace Hobby Distributor, United Hobby Distributor, Horizon Hobby Distributor, and once upon a time before they went belly up, Great Planes Model Distributors (told you it was a tough business). There are others.

So these guys typically work on a 25% margin. And they earn their daily bread, believe me. Why? It’s because they have big expenses like people manning phone banks, account managers, many, many employees, plus warehouses, fork lifts, etc. They’re calling on hobby shops non-stop and making it easy for them to buy for stock.

So doing the math again we begin with the $54 the hobby shop owner paid, and the math works out to $54*0.75=$40.50. So now we have an idea of how much the distributor pays for it. So if they pay about $40.50 for the servo, then who’s next in the wetting their beak line? The importer, of course!

An importer may operate on a 15% margin. So continuing to work backwards from $40.50*0.85=$34.43 and now we know about what the guy who bought it from the Asians paid them (give or take because there’s air freight involved, also).

Does this mean the guy who makes it is seeing $34.43 for his product, right? Maybe, maybe not. Why not? It’s because in east Asia there are outfits called seller’s agents.

Seller’s agents operate on a 5% margin. Really common practice and what they do is speak English, which some machine shop owner Shenzhen may not. So the seller’s agent earns his cut by acting as an interface with Americans who don’t speak Vietnamese, Chinese, Malay, or whatever.

So doing the simple math once again, we take $34.43*0.95=$32.70 and from this, the guy has to make his rice bowl work. E.g. buy bar stock, end mills, pay the light bill, buy potentiometers, motors, produce PCBs, buy bolts, pay for labor for assembly, mortgage payment on his plant, office employees, pay his taxes, and make a profit.

Suspect if he sees $15-17 he did well so a product costing you $90 is costing about $17 to actually make. So the price you’re paying actually involves paying for the function of the distribution chain. You’re paying for the business model. One, which puts the product in the store (or in this case, into a model airplane or maybe a model helicopter). Whatever.

Potentiometer

With us, none of these other guys getting a cut means we spend more making the product. It’s why we can pony up $12 for a potentiometer, as an example. The best in the trade is the Nobel 1mc, which is what you get.

Think about it, do you believe someone making a servo for $17 and selling same for $34 can fork over $12 for just a pot? If you ever wondered why some of the no-name new players in the servo business offer such tantalizing technology as magnetic pots? Now you know a bit more about why . . . it’s always down to money.

Want to learn more about the subject? Then review this brief article:

• About pots vs Hall Effect sensors

Major point being, if you’re not getting the Noble 1mc, then what the Hell are you getting for your $90? And is it as good as the 1mc? That’s a reasonable question. Do these guys talk even about it when discussing the product?

Wrapping up

So how does the Theta THM989 stack up against the ProModeler DS405BLHV in your eyes? How about putting it against the DS210CLHV? Speaking of which, the fellow who started the ball rolling on this white paper opted for the DS160CLHV despite my guiding him toward the DS210CLHV.

Honestly? Had it been a 60in model instead of a 67in I would have happily guided him to the DS160CLHV but the larger wingspan, as with the Turbo Raven in my estimation merits more oomph. This is probably why EF also guide you to the lovely MKS HV747.

And that servo truly is a very well made product . . . wanna take a guess how I know? Yup, we bought some to compare with our DS205BLHV to offer up another matchUP for the curious.

Want to to know what other servo makes about the same torque and also competes with the lovely MKS HV747? Yup, another Theta product, their THM988.

And guess what? This means we turn our gun sights on it as well since we have both our DS205BLHV and DS210CLHV in this space. So we have another matchUP for if you’re curious about it, also!

Circling back around to Andrew’s pal, he decided the DS160 best suited him best using considerably less information than you now have, now. For him it was enough to make an informed judgement regarding which servo was suited him and his budget.

And that’s the point, helping him do what was best for him. And helping you decide on what’s best for you!

Honestly? I think our servos are better than the Theta product. Not even close. But my opinion doesn’t amount to the proverbial hill of beans because the fellow reaching for the scratch to pay for them is you. What do you think?

Means the only opinion that matters is yours! I say this over and over because it’s true.

Recapping:

Let’s list what we’ve touched on. Six servos offered up against what Extreme Flight offers you. To their basic specs and prices;

• THM989 – 320oz-in @ 0.07sec/60° – $90
• MKS HV747 – 208oz-in @ 0.13sec/60° – $100

We touched on six ProModeler servos, which included;

• DS110CLHV – 110oz-in @ 0.035sec/60° – $50
• DS160CLHV – 160oz-in @ 0.06sec/60° – $60
• DS210CLHV – 210oz-in @ 0.06sec/60° – $70
• DS205BLHV – 205oz-in @ 0.052sec/60° – $80
• DS355CLHV – 355oz-in @ 0.08sec/60° – $90
• DS405BLHV – 405oz-in @ 0.055sec/60° – $100

As you can see, two make less torque, two make more torque, all but one are faster, and four of the six cost less. What you get with our three least expensive includes;

• Allen head fasteners
• 13 seals and o-rings
• Bronze hard points
• Boxing the output shaft
• Stainless steel gear train
• Finned aluminum center case
• Potting compound
• Eight MIL-STD

Final thoughts

Allow me offer a few final thoughts. The right servo for you is a reflection of yourself, your goals, your dreams, and your budget. We work hard put a better grade of servo in your hands. But nobody can make you buy them. This you decide for yourself.

Still have questions? Feel free to reach out – we’re readily available;

• Telephone: 407-302-3361
• Email: info@promodeler.com

. . . then maybe together we can suss out what’s best for you!

I’ll close with this, one thing’s certain, best is a race that’s never finished. Best right now? ProModeler, but already Theta have more marketplace buzz. Deserved? Yes, they worked hard for it.

Are their servos worth your money? Not our decision. Not even theirs, either. Your decision, and yours alone.

Anyway, if you end up trying our servos and like them, then do us the favor of taking one to a club meeting. Pass it around. Maybe even pull out a 1.5mm Allen driver and open it up. While not the same same servo, this article shows how they go together;

• On rebuilding damaged DS505s

So what you’ll be reading about are a pair of servos a guy beat the ever living shit out of. Because they had steel bushings, the cases weren’t damaged and all he was on the hook for were a set of gears (he sent them in, we don’t charge labor). So we took photos as we disassembled and cleaned them, put them back together and lubed before buttoning them back up and returning them to the customer. Those come apart and go back together the same way and once you’ve seen one, you’ve seen them all. It’s not rocket science, believe me.

Saying there’s nothing to be afraid of in opening one up at your club meeting. Also, please, show them to a pal. But most of all, kindly grace us with a photo sharing your thoughts. What for? To put on the website, and within articles like this. Basically, for telling the next guy what you like about our servos.

What we’re Jones-ing for are photos like this one because your favor is priceless and can’t be bought. We know this. So do others.

Last thing

Have you enjoyed this? If you like reading and are interested in learning more, then maybe find time to review more articles like this;

• matchUP: Hitec D645MW vs DS180DLHV
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